Australia are out of the under-19 Cricket World Cup finals race after going down to South Africa by 80 runs in Dubai.
The loss means Australia will now play off for third place against England on Friday.
Six wickets to South African quick Kagiso Rabada didn't let the Australian batsmen settle in their chase of 231.
Rabada's raw pace clocked up speeds of more than 140kph and undid Matt Short (7), Jaron Morgan (12) and Damien Mortimer (4), leaving Australia in trouble early.
Jake Doran teamed up with captain Alex Gregory for a 53-run stand, but when Gregory (31) and Doran (36) departed, the run rate required lifted to more than six an over.
Ben McDermott looked up to the task and was off the mark with a four, followed shortly by a towering six, but headed back to the sheds for 12 after a mix-up with partner James Bazley caught him short of his crease.
Bazley set himself for one of his trademark power innings, but his stand of 22 from 26 balls came to an end when he was bowled by a Yaseen Valli yorker.
Rabada re-entered the attack and added Tom Andrews (4), Ben Ashkenazi (0) and Guy Walker (4) to his victims' list, finishing with an impressive 6-25 and the man of the match award.
Australia were bowled out for 150 in 42.2 overs.
Earlier, the Australian bowlers mounted a late fight-back to peg South Africa to 9-230.
The South Africans were cruising at 0-105 as openers Clyde Fortuin (74) and Aiden Markram (45) worked the ball around with control.
A stunning one-handed diving catch from Walker at point, off the Bazley's bowling, opened Australia's wicket account, but it wasn't until spin was introduced that the Aussies made inroads.
Short's off-spin produced immediate results, snaring the wicket of innings top-scorer Fortuin with his first ball.
Short gave the batsmen little opportunity to free their arms and was rewarded shortly with another victim, this time Kirwin Christoffels (20) spooning it to Gregory at gully.
Short finished with the best Australian bowling figures with 2-14 from his seven overs.
Billy Stanlake (2-36) and Ashkenazi (2-37) also grabbed two wickets apiece, but it wasn't enough for Australia.
